**multiple platform you check and run your code according specific platform **

bool isIOS = Theme.of(context).platform == TargetPlatform.iOS;
bool isAndroid = Theme.of(context).platform == TargetPlatform.android;
bool islinux = Theme.of(context).platform == TargetPlatform.linux;
bool isfuchsia = Theme.of(context).platform == TargetPlatform.fuchsia;
bool isMacOS = Theme.of(context).platform == TargetPlatform.macOS;
bool iswindows = Theme.of(context).platform == TargetPlatform.windows;

import 'dart:io' show Platform;

if (Platform.isAndroid) {
  // Android-specific code
} else if (Platform.isIOS) {
  // iOS-specific code
}

所有选项包括:

Platform.isAndroid
Platform.isFuchsia
Platform.isIOS
Platform.isLinux
Platform.isMacOS
Platform.isWindows

你也可以使用kIsWeb来检测你是否在web上运行，kIsWeb是一个全局常量，指示应用程序是否被编译为在web上运行:

import 'package:flutter/foundation.dart' show kIsWeb;

if (kIsWeb) {
  // running on the web!
} else {
  // NOT running on the web! You can check for additional platforms here.
}

平台文档:https://api.flutter.dev/flutter/dart-io/Platform-class.html kIsWeb文档:https://api.flutter.dev/flutter/foundation/kIsWeb-constant.html

导入io库很简单

import'dart:io' show Platform;
void main(){
if(Platform.isIOS){
  return someThing();
}else if(Platform.isAndroid){
  return otherThing();
}else if(Platform.isMacOS){
  return anotherThing();
}

或者用非常简单的方式

Platform.isIOS ? someThing() : anOther(),

如果你同时导入"dart:io"和"dart:html"，它不知道要导入哪个平台并给出错误。导入其中一个。

import 'dart:io';
Platform.isIOS ? CupertinoWidget() : MaterialWidget()

感谢科林，最终答案是:

bool isIOS = Theme.of(context).platform == TargetPlatform.iOS;

您可以将这个扩展文件(platform_ext.dart)添加到项目中并调用任何对象

import 'dart:io';
import 'package:flutter/foundation.dart' show kIsWeb;

extension Target on Object {
  bool isAndroid() {
    return Platform.isAndroid;
  } 
  bool isIOS() {
    return Platform.isIOS;
  } 
  bool isLinux() {
  return Platform.isLinux;
  } 
  bool isWindows() {
  return Platform.isWindows; 
  }
  bool isMacOS() {
  return Platform.isMacOS; 
  }
  bool isWeb() {
  return kIsWeb; 
  }
  // ···
}

只需导入文件并调用它

   import 'platform_ext.dart';
        ....
        @override
          Widget build(BuildContext context) {
            return isAndroid()? Text("Android"):Text("Not Android");
          }